Here's when we will really notice rugby's Regulation 8 Effect – it's sooner than you might think

Player eligibility changes will hit long before the December 31, 2020, date mentioned in the press, writes James Harrington.

December 31, 2020. It's a Thursday. And, on May 10, 2017 – last Wednesday – it was etched in rugby stone.

On this particular distant Thursday, World Rugby's Regulation 8 changes – upping the qualifying residency period from 36 months to 60 months. Or from three years to five years, if you want to put it that way.

It has prompted confusion, that otherwise innocent and unassuming date that was unanimously agreed at a meeting in Kyoto, Japan, shortly before the draw for the 2019 World Cup.

Some have wondered why the law could not come into force earlier. After all, there are plenty of Thursdays – and Wednesdays, Sundays, Fridays, Tuesdays, Saturdays and Mondays – between now and then.

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The truth is, we will feel the Regulation 8 Effect much sooner than that, World Rugby has confirmed to Rugby Pass. End-of-the-year sooner, in fact.

December 31, 2020, is not an arbitrary future Thursday that the old farts in suits and Agustin Pichot plucked out of the ether. It's about as near to now as it's reasonably possible to get.

That date is the splash where World Rugby's player eligibility stone hits the water.

The ripples that stone causes extend back in time - to December 31, 2017. A Sunday. That's the absolute, definitive, final date at which it is possible for players to complete three years of residency before the 2020 change takes effect.

After this date, qualification periods cross the 2020 threshold. So, players who move from one country to another from 2018 onwards must complete five years' residency before they can play for the national side of their adopted home.

The delay is to allow players already in the system, such as Munster's New Zealand-born hooker Rhys Marshall, and others who may have already agreed to enter the system later this year, to complete their qualifying period under existing regulations.

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